Paperboard Three-Dimensionally Molded Pallet

ABSTRACT

A paperboard three-dimensionally molded pallet having sufficient rigidity in its load carrying surface and load bearing strength in its leg portions. The pallet is so designed that when it is finally treated as a waste, it can be recycled as new paperboard three-dimensionally molded pallets or a material for the other paper products requiring rigidity. The pallet comprises a paper-made plate-like top plate member ( 1 ) and paper-made cylinder-with-base legs ( 2 ). A plurality of through holes ( 15 ) is provided in the top plate member ( 1 ), and the cylinder-with-base-type leg ( 2 ) is inserted into the through hole ( 15 ) and then joined to the top plate member ( 1 ) with a water soluble adhesive agent. The top plate member ( 1 ) and the cylinder-with-base-type leg ( 2 ) are produced by placing a water-absorbed plane laminated paper as a raw material in a mold to shape it into a specific shape by thermal dehydration under pressure process.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a paperboard three-dimensionally molded pallet used for carrying loads by using forklifts etc., and more particular to a sturdy paperboard three-dimensionally molded pallet made from a recyclable material and having an excellent surface hardness and load bearing strength.

BACKGROUND OF THE INVENTION

Wooden pallets have been generally used as pallets for carrying loads by using forklifts. However, decrease in the usage of wood is considered to be desirable, because reduction in forests has recently been an international social issue. Further, there are difficulties in disposal of the wooden pallets, and fumigation works for the wooden pallets is also inevitable for insect proof, so that these additional works and costs are needed, being inconvenient.

From these points of views, pallets mainly made of corrugated board have been used recently instead of the conventional wooden pallets. These pallets made of corrugated board are easy to dispose and the use of such pallets are desirable from a viewpoint of paper recycling. However, this type of pallets has shortcomings, low in strength in load carrying surface, so that usable load range is somewhat limited (Refer to Patent Document 1).

Pallets are inevitably provided, on the rear side of a deck board, with a fork insertion space, using legs or beams, into which forks of forklifts are inserted. However, the strength of the legs or beams made of the corrugated board is usually low so that the legs or beams are easily damaged under an impact shock during load carriage, causing the fork insertion space to be diminished and the pallets become unusable. Therefore, the rigidity of the load-carrying surface has strengthened by using such as plastics or metal fixing jigs to the leg portions (Refer to Patent Document 2).

Furthermore, as a method to provide molded paper articles using refuse paper and having various curved surfaces with a sufficient strength, there has been proposed one method to produce pallets made of mainly refuse paper. The method includes firstly providing a colloidal state refuse paper solution, molding the solution in a mold through vacuum dewatering process to obtain legs made of the refuse paper, and then bonding a load-carrying surface to the leg portions under pressure. The leg portions molded by the laminated refuse paper are made of such material used for egg-protective cases, which do not have a sufficient physical strength nor surface hardness which can endure thrust of forks of forklifts. (Refer to Patent Document 3).

-   Patent Document 1: Japanese Unexamined patent publication H06-171648     A1 -   Patent Document 2: Japanese Unexamined patent publication     2002-370740 A1 -   Patent Document 3: Japanese Unexamined Patent Publication H07-285185     A1

DISCLOSURE OF THE PRESENT INVENTION Problems to be Solved of the Present Invention

In order to solve the deforestation issues, recycling problems of discarded pallet material, fumigation problems etc., paper-made pallets made of corrugated board or refuse paper, as mentioned above, has been drawn our attention. However the practical use of the paper-made pallets is somewhat limited because the load-carrying surface and the leg portions are low in rigidity and in strength.

Therefore, the present invention is to provide a paperboard three-dimensionally molded pallet with the load-carrying surface having practically sufficient rigidity and a leg portion having a sufficient load bearing strength as a pallet. And the present invention is to provide a paperboard three-dimensionally molded pallet that is capable of recycling as a new paperboard three-dimensionally molded pallet or other paper products requiring sufficient rigidity with no need for each member to be sorted by material when it is finally treated as a waste.

Means to Solve the Problems

The above problems can be solved by providing a paperboard three-dimensionally molded pallet according to a first aspect of the present invention in which the pallet comprises:

-   a plane top plate member made of paper; and -   a cylinder-with-base type leg member made of paper; -   wherein a plurality of through holes is provided in the top plate     member, -   a portion of the leg member is inserted into the through hole and     joined to the top plate member using water soluble adhesive, the top     plate member and the leg member are made through a highly-compressed     molding process in which a water-absorbed plane laminated paper as a     raw material is placed into a mold and then molded into a prescribed     shape through a pressurized thermal dehydration process.

The second aspect of the present invention is characterized in that in addition to the first aspect, the top plate member is formed with a rising sidewall at a side end portion thereof, and on a plane portion of an inner side of the sidewall, a reinforced corrugated board is joined using a water soluble adhesive.

The third aspect of the present invention is characterized in that in addition to the first aspect, the top plate member comprises:

-   a plate-like core material having convexo-concave shape in cross     section; and -   a plate-like outer member having a size capable of covering a top     surface and/or a rear surface of the core material, the plate-like     outer member being arranged on and joined to the core material using     a water soluble adhesive.

The fourth aspect of the present invention is characterized in that in addition to any one of the aspects 1 to 3, the cylinder-with-base-type leg member comprises:

-   a round bottom surface; -   a wall surface having an arcuate shape in cross section, which rises     upward from the round bottom surface; and -   an outward flange extending horizontally outward from the wall     surface, -   an upper surface of the top plate member and the flange portion of     the leg member are joined together.

The fifth aspect of the present invention is characterized in that in addition to the fourth aspect, the wall surface of the leg member has a plurality of divided wall surfaces divided into 3 to 8 along a circumferential direction of the leg member, and adjacent side edges of the divided wall surfaces are contacted with or placed close to each other.

The sixth aspect of the present invention is characterized in that in addition to the fifth aspect, a plurality of the cylinder-with-base type leg members are superimposed in such a way that the side edges of the superimposed divided-wall surfaces of the respective leg members are arranged along the circumferential direction without overlapping with each other.

The seventh aspect of the present invention is characterized in that in addition to any one of the aspects 1 to 6, at a circumferential portion of the through hole of the top plate member, a concave portion having a depth with the same dimension as that of the thickness of the flange portion is provided.

The eighth aspect of the present invention is characterized in that in addition to any one of the aspects 1 to 7, a bottom plate having a size large enough to join all the leg members are joined to the bottom surfaces of the leg members using water soluble adhesive.

Effects of the Present Invention

According to the paperboard three-dimensionally molded pallet of the first aspect, the surface hardness of the pallet is made high, so that the pallet is not stabbed by the fork of the forklift when the top plate or leg portion is thrust, being able to realize an efficient load carriage. Further, the highly-compressed molded article itself is excellent in strength, and the cylindrically formed leg member is inserted into the through hole of the top plate member and then joined there so that the top plate member tightens the three-dimensionally molded cylindrical leg member to thereby prevent the leg member from being collapsed by loads and to prevent the pallet from becoming unusable due to the collapse of the leg member caused by an impact shock during load carriage. Thus the paperboard three-dimensionally molded four-way pallet is produced. When it is finally treated as a waste, there is no need to sort parts out by material. The waste pallets can be recycled only by immersing the waste pallets into water to dissolve them as raw material for a new paperboard three-dimensionally molded pallet or other paper products requiring high rigidity.

According to the paperboard three-dimensionally molded pallet of the second aspect, in addition to the effects of the first aspect, the reinforced corrugated board is joined to the upper surface of the top plate using water soluble adhesive. Therefore, the flange portion of the leg portion is adhered to the top plate member from upper and lower side, being able to provide a leg having high strength while the leg is made as an independent part. If desired, a load carrying surface, which has an appropriate strength corresponding to the weight of a load, of a paperboard three-dimensionally molded pallet can be prepared on site by preparing previously one or multiple cut-out sheet(s) of predetermined-size reinforced-corrugated board and laminating it on the pallet. Since the corrugated board is made of paper, recycling properties of the pallet is not damaged even if corrugated board is laminated. In addition, a cut surface of the corrugated board is protected by the rising side wall of the top plate member having a high surface hardness so that such an inconvenience as stabbing of the forks into a conventional corrugated board pallet can be avoided, being able to realize an efficient load carriage.

According to the paperboard three-dimensionally molded pallet of the third aspect, in addition to the effects of the first aspect, the core material comprising a paper-made highly-compressed molded article and the outer surface member are joined to the upper surface of the top plate using water soluble adhesive. Therefore, the flange portion of the leg is adhered to the top plate member from upper and lower side, being able to provide a leg having high strength while the leg is an independent part. In addition, since the top plate member has structural rigidity, the strength of the load-carrying surface is improved and pallets for heavy load bearing can be realized without damaging recycling characteristics.

According to the paperboard three-dimensionally molded pallet of the fourth aspect, in addition to the effects of the first to the third aspects, the leg member is a cylinder-with-base type leg member which comprises: a round bottom surface; a wall surface having an arcuate shape in cross section, which rises upward from the round bottom surface; and an outward flange extending horizontally outward from the wall surface. Therefore, the leg can have the highest possible structural rigidity, and make best use of the physical strength of the material made from the plane laminated paper by way of a pressurized thermal-dehydration process.

One can easily conceive that good structural rigidity can be theoretically obtained when the leg is formed to have a cylindrical shape. However it is considerably difficult to produce a cylinder-with-base-and-flange type molded article having no crack and made of a plane laminated paper with almost no plasticity. The present inventors invented a method to produce three-dimensional articles from a plane laminated paper (Japan unexamined Published patent 2000-177033A1) The fourth aspect of the present invention basically adopts this producing method. In the fourth aspect, a certain length and a number of cutouts (or notches) corresponding to the thickness of the plane laminated paper are made in the plane laminated paper so that the cylinder-with-base-and-flange type leg having a bending portion on the surface thereof can be produced without causing a crack in the plane laminated paper. According to the fourth aspect, the leg member having an excellent load-bearing strength which has not been attained in the conventional articles made of paper, can be provided. A sturdy paperboard three-dimensionally molded pallet made of paper can be produced.

According to the leg member of the fifth aspect, in addition to the fourth aspect, the wall surface of the cylinder-with-base-and-flange type leg is divided into 3 to 8 along a circumferential direction of the leg member, and adjacent side edges of the divided wall surfaces are contacted with or placed close to each other, so that when the cylinder-with-base-and-flange type leg is inserted into the through hole and joined, the divided wall surfaces are formed into one rigid body in total, as if a barrel is fastened with hoops, being able to provide a strong leg member.

According to the leg member of the sixth aspect, in addition to the fifth aspect, a plurality of the cylinder-with-base type leg member are superimposed and the side edges of the superimposed divided-wall surfaces of the leg members are arranged along the circumferential direction without overlapping with each other. Therefore, each divided portion is covered up (or boarded up) by other wall surface and is strengthened. Each cylinder-with-base type leg becomes totally seamless and strengthened. There is no gap or opening that communicates inside and outside of the cylindrical leg, preventing intrusion of foreign materials or water into the inside of the cylindrical leg, improving durability thereof.

According to the paperboard three-dimensionally molded pallet of the seventh aspects, in addition to the effects of any one of the aspects 1 to 6, a concave portion having a depth with the same dimension as that of the thickness of the flange portion is provided at a circumferential portion of the through hole of the top plate, therefore, when the leg member is inserted into the through hole and then joined to the top plate member, the upper surface of the top plate member and the upper surface of the flange portion will have the same flat level. Under such structure, when the reinforced corrugated board or the core material is joined using water soluble adhesive, not only adhering area becomes large but also the rigidity of the top plate member can be improved. The flange portion of the leg member is also closely adhered from upper and lower side to the multiple-layered top plate member so that the strength of the top plate member itself and a base portion of the cylinder-with-base-and-flange type leg is also improved. The independent leg is further stabilized.

According to the paperboard-three-dimensionally molded pallet of the eight aspect, in addition to any one of the effects of the aspects 1 to 7, a bottom plate having a size large enough to join all leg members is joined onto the bottom surfaces of the leg members using water soluble adhesive, therefore, the pallet itself becomes more three-dimensional, the rigidity of the pallet is further improved and the strength of the load carrying surface is also further improved. Further, when loads are piled up, such inconvenience as an occurrence of indentation produced by the legs can be prevented.

BRIEF EXPLANATION OF THE DRAWINGS

FIG. 1 is a perspective view showing an exterior view of a paperboard three-dimensionally molded pallet according to a first embodiment of the present invention.

FIG. 2 is a cross sectional view showing a substantial portion of a joining portion between a leg member and a top plate member of the first embodiment.

FIG. 3 is a cross sectional view showing a substantial portion of a second embodiment of the present invention.

FIG. 4 is a cross sectional view showing a substantial portion of a third embodiment of the present invention.

FIG. 5 is a perspective view showing a cylinder-with-base type leg of the first embodiment.

FIG. 6 is an example of a cut paper pattern of the cylinder-with-base type leg of the first embodiment.

FIG. 7 is a perspective view showing an exterior view of a fourth embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION

The paperboard three-dimensionally molded pallet of the present invention will be explained hereunder with reference to FIGS. 1 to 7.

First Embodiment

FIG. 1 is a perspective view showing an exterior view of a paperboard three-dimensionally molded pallet according to a first embodiment of the present invention.

The first embodiment comprises a plane top-plate member 1 and nine cylinder-with-base type legs 2 inserted through the top plate member 1. A flange portion provided at a peripheral portion of the cylinder-with-base type legs 2 are bonded to the top plate member 1.

FIG. 2 is a cross sectional view showing a substantial portion of the first embodiment 1.

In the top plate member 1, a through hole 15 through which the cylinder-with-base type leg 2 is inserted is provided. The hole is designed to have such a diameter that an outer diameter of the base portion of the cylinder-with-base-type leg 2 is tightly fitted. At a circumferential (peripheral) portion of the hole, a concave recess 16 having a depth with the same dimension as that of a thickness of the flange portion is provided. When the top plate member 1 and the cylinder-with-base type leg 2 are joined with adhesive, an upper surface of the top plate member 1 and an upper surface of the flange of the cylinder-with-base-type leg 2 is designed to have the same level (or to be on the same flat level), preferably.

In cases where the upper surfaces of both the top plate member 1 and the flange portion of the cylinder-with-base type leg 2 are structured to have the same level and where a reinforced corrugated board 5 and/or a corrugated-plate-core material 4 is bonded on the upper surface of the top plate member 1 using water soluble adhesive, a joining area between the reinforced corrugated board 5 or the corrugated-plate-core material 4 and the top plate member 1 can be larger because a joining surface is made flat (as seen in FIG. 3 or 4). In addition, the flange portion of the cylinder-with-base type leg 2 is closely bonded to an upper and lower side of the reinforced top plate member, therefore, the top plate member is reinforced and an attaching portion of the cylinder-with-base-type leg 2 is reinforced. The independent leg is further stabilized.

The top plate member 1 and the cylinder-with-base-type leg 2 can be produced by a compression molding method described in Japanese unexamined published patent 2000-177033 A1 filed by the present inventors, in which high-precision three-dimensional press molding method or other similar compression molding method using paper as a raw material is disclosed.

Generally, the plane laminated paper has a property that the fiber is oriented in a specific direction when the paper is manufactured. Therefore, the completed plane laminated paper has directionality and the bending strength may vary largely with the bending direction. To obtain a top plate member 1 having an approximately equal bending strength in every direction, every plane laminated paper should be laminated on the other with shifting the paper by a specific degree so that the fiber direction of paper is changed for every plane laminated paper (for example, four plane laminated papers each is shifted by 90 degrees from the previous paper and are all then laminated together). According to this procedure, unequal deformation characteristics of bending or shrinking arising in the conventional molded plane paper are reduced. As a result, a paperboard three-dimensionally molded article having a uniform bending strength and rigidity in every direction and no curvature deformation can be obtained. Lamination can be carried out by making the plane laminated paper absorb water, applying adhesive on a surface to be laminated and then subjecting it to high compression molding

As adhesive, a water-soluble vinyl acetate base can be used. Specifically, Pegal 210PR, Pegal 100HHR, Pegal 1540 and Pegal 517R (products by Koatsu Gas Kogyo Kabushiki Kaisha) can be exemplified. It is confirmed that these adhesives meet the Codes and Standards of Food Sanitary Law: Food Additives (The No. 370 Notification by the Ministry of Health and Welfare in the 34 year of Showa Era). Burden of these adhesives to workers and the environment is light. These adhesives can be used by diluting them with water in a volume ratio of 10% to 100% in order to improve workability.

By using the water soluble vinyl acetate adhesive, the paperboard three-dimensionally molded pallet including all the construction members such as the top plate member 1, the cylinder-with-base-type leg 2, and adhesive can all be dissolved in water, and can be recycled easily as a raw material for a new plane laminated paper.

FIG. 5 is a perspective view showing a cylinder-with-base type leg 2 of the first embodiment of the paperboard three-dimensionally molded pallet.

FIG. 6 is an example of a cut paper pattern which is produced by cutting a plane laminated paper and is to be subjected to high compression molding to prepare the cylinder-with-base type leg 2. The cylinder-with-base type leg 2 is formed by high compression molding method in which a sidewall is raised by valley folding along a dashed line 19 and the flange portion is opened outward by mountain folding along a dashed dotted line 20.

In order to avoid generation of a crack at a bending portion during compression molding, water is absorbed before molding of the raw paper pattern 6 with a water ratio of 40 to 90%, then the water absorbed raw paper pattern 6 is set into a mold with an upper and lower mold having cylinder-with-base-and-flange shape in cross section, corners of which have a round shape (R shape) of a predetermined size. The raw paper in the molds are continued to be pressurized under a pressure of about 1 ton/cm^(2,) at a temperature of 100 to 250° C. using a compression molding machine which can perform a pressurized thermal dehydration process until water content of the paper becomes 2 to 3%.

The compression molded articles having an excellent mechanical properties can be obtained when a compression rate in the compression molding is in the range of 70 to 80% for a plane laminated paper having a thickness of 1 to 3 mm, 50 to 70% for a plane laminated paper having a thickness of 3 to 30 mm or 3 mm or more when a plurality of paper is laminated. The compression rate is calculated on the basis of that the thickness of the non-water absorbed paper is set to 100%. When a plurality of the plane laminated paper are laminated, adhesive is applied on the surface to be laminated. It is noted that when water is added up to more than 30% to the adhesive, the strength of the molded articles is lowered by 10% or less. In order to obtain a molded article having excellent mechanical properties, undiluted adhesive should be used. On the contrary, when workability is emphasized more than other things, diluted adhesive may be used accordingly.

An open angle of the cutout 18 for forming wall surface, which is provided in the raw pattern paper 6 of the cylinder-with-base type leg 2 is adjusted in accordance with the number of wall surfaces, rising angle of the wall surface and thickness of the plate of the raw pattern paper 6, so as not to cause generation of an aperture between the adjacent wall surfaces as far as possible (desirably adjacent side edges of the wall surfaces are tightly contacted and fitted with each other like barrel when the barrel is bounded up with hoops). For example, when the cylinder-with-base type leg 2 having five sheets of wall surfaces and a wall surface's rising angle of 83 degrees is formed from a 4 mm-thick board, the side edge surfaces of the adjacent wall surfaces of a cylinder-with-base type leg 2 can be arranged in such a way that the side edge surfaces are contacted with or close to each other by setting the open angle of the cutout 18 of the raw pattern paper 6 at 65 degrees. In cases where there is a small clearance gap between the wall surfaces of the molded cylinder-with-base type leg 2, no problem occurs when the wall surfaces can be tightly contacted with each other after the leg 2 is inserted into the through hole of the top plate.

The number of the divided wall surfaces should be as few as possible to ensure the load-bearing strength of the cylinder-with-base type leg 2. However, even if moisture is absorbed, the plane laminated paper does not show much plasticity or drawing property so that forcible molding causes cracks in the molded articles. Generally, when the wall thickness of the raw pattern paper is about 1 mm, molding can be conducted with three pieces of the wall surfaces. When the wall thickness of the raw pattern paper is more than 10 mm, eight pieces of wall surface are needed. In the present invention, it has been confirmed that the cylinder-with-base-type leg 2 has a maximum load strength of more than 530 kg when 6 mm-thick plain laminated paper is used. In order to obtain a leg having a normal load-bearing strength, a 4 mm- to 6 mm-thick plain laminated paper can be used. When 2 to 3 sheets of 2 mm-thick plane laminated paper are laminated and used, the divided wall surface number is preferably 5 to 6.

Rising angle of the wall surface of the cylinder-with-base type leg 2 is preferably set at 90 degrees when only considering a vertical load strength. The leg of the pallet is subjected to horizontal rolling load when transported by truck. Therefore, the leg is made into a cylindrical shape like a drinking cup so as to strengthen against horizontal rolling load. In this case, a preferable rising angle of the wall surface of the cylinder-with-base type leg 2 is in the range of 70 to 89 degrees. Under 70 degrees, a vertical load resistance strength is deteriorated. Over 90 degrees on the contrary, a stress of the horizontal rolling load is concentrated at the attaching portion of the flange, so the base portion of the leg could be bent occasionally. A preferable angle is within the range of 78 to 86 degrees.

Further, in case where the rising angle of the wall surface of the cylinder-with-base type leg 2 is set at 90 degrees and the wall surface exactly stands vertically in the form of exact cylindrical shape, the leg can be reinforced by fitting a paper tube having an inner diameter equal to the outer diameter of the leg onto the leg surface. When there is no problem such as an increase in the number of parts or the cost, such a structural change can be adopted.

The depth of the cutout 17 of the bending portion of the outward flange of the cylinder-with-base type leg 2 should be determined according to the thickness of the raw pattern paper 6 to be used. When the thickness is large, the depth of the cutout should be made deeper because being shallow in depth of the cutout causes cracks on the wall surface. However when the cutout is made too deep, the strength of the leg is deteriorated, accordingly the depth should be adjusted so as not to cause cracks. Preferably, the depth of the cutout is set at 1.5 to 2 times long as an overhanging length of the flange. The number of cutout is one per wall surface for less than 5 mm-thick raw paper and two per wall surface for more than 5 mm-thick raw paper, when the wall surface is divided into five. When the number of the cutout is increased and the depth of the cutout becomes deeper, molding can be conducted easier but the strength of the resulting article is deteriorated.

The cylinder-with-base type leg 2 made by the above method is inserted into the through hole provided in the top plate member 1 and the flange portion is joined to the top plate member 1 using water soluble adhesive, thus the paperboard three-dimensionally molded pallet of the first embodiment is obtained.

EXAMPLE 1

To confirm load bearing strength of the cylinder-with-base type leg 2, a cylinder-with-base type leg 2 having five divided sidewalls, 100 mm-outer-diameter bottom surface, 120 mm-outer-diameter flange base and 100 mm height is molded from 6 mm-thick raw pattern paper 6. A maximum compressive load test for each leg member was conducted according to an embodiment corresponding to the first embodiment. As Comparative Example, a pentagonal type tubular legs having a pentagonal bottom surface and plane plate sidewall were molded in a similar fashion as Example 1 from the raw pattern paper 6 used in Example 1.

TABLE 1 Comparative TEST No. Example 1 Example 1 No. 1 538 366 No. 2 545 358 No. 3 550 369 Average 544 364 (Unit: kg)

From Table 1, the cylinder-with-base type leg 2 formed from 6 mm-thick raw pattern paper 6 has a maximum compression-load strength of 544 kg. On the other hand, the pentagonal type tubular legs that was formed from the same raw pattern paper 6 and having the plain sidewall has only a maximum compression-load strength of 364 kg.

EXAMPLE 2

To confirm the load bearing strength when the cylinder-with-base-type legs 2 are superimposed, two types of the leg 2 were formed. In Example 2, the leg was formed by superimposing two 2 mm-thick raw pattern papers 6 in such a way that joint portions of the divided wall surface were not overlapped and in Comparative Example 2, the leg was formed by overlapping all the joint portions. Each cylinder-with-base-type leg 2 had five divided sidewalls, 100 mm-outer-diameter bottom surface, 120 mm-outer-diameter flange base and 100 mm height. The maximum compression load tests were carried out.

TABLE 2 Comparative Test No. Example 2 Example 2 No. 1 402 358 No. 2 410 355 NO. 3 394 361 Average 402 358 (Unit: kg)

From Table 2, the leg of Example 2, in which the cut portions of the divided wall surfaces of the raw pattern paper 6 were not overlapped, had a maximum compression load strength of 402 kg. On the other hand, the leg of comparative Example 2, in which the cut portions of the divided wall surfaces were overlapped, had a maximum compression load strength of 358 kg. In addition, adhesive containing 20% by volume of water was applied on the joined surfaces of the water absorbed raw pattern papers 6. If undiluted adhesive was used, the mechanical strength can be further improved.

Second Embodiment

FIG. 3 is a cross sectional view showing a substantial portion of the second embodiment of the present invention.

In the second embodiment, at the side end portion of the top plate member 1 of the first embodiment, a side end rising portion 8 having a predetermined height is formed. To the inside of the rising portion 8 of the side end portion, a commercially available reinforced corrugated board 5 was adhered using water soluble adhesive.

In the second embodiment of the present invention, the commercially available reinforced corrugated board 5 is adhered to the top plate to strengthen the top plate. As for the reinforced corrugated board 5 to be adhered, any one of the laminated-reinforced corrugated boards having one layer to multi-layer can be used for backing up the top plate member in accordance with the weight of the load to be carried.

The height of the rising portion 8 of the side end portion is preferably taller than the thickness of the reinforced corrugated board 5 to be adhered. The rising portion is used as a wall for preventing the load from falling down and also used as a wall to prevent the forks of the forklift from thrusting into the cut surface of the corrugated board.

The size of the raw plane laminated paper to be used for the top plate member 1 can be adjusted in accordance with the height of the rising portion 8 of the side end portion so that the area of the load-carrying surface of the top plate member 1 does not become small.

Third Embodiment

FIG. 4 is a cross sectional view showing a substantial portion of the third embodiment of the present invention.

The pallet of the first embodiment has a minimum function as a pallet. When it is not used for carrying a heavy load, the pallet itself is required to be light in weight and good in handling. However, if the pallets are used for carrying heavy loads, as is the case with wooden pallets, pallets with load carrying surface having high strength and rigidity as shown in the third embodiment is needed.

In the third embodiment, a corrugated-plate-like core material 4 is adhered to the top plate member 1 and an outer surface member 3 is further adhered to the corrugated-plate-like core material 4 so that the top plate member 1 is made into a double layered top plate member. Therefore the strength of the top plate member is improved. And it can be used for carrying heavy loads.

The core material, that is made of paper having a certain height and can define a clearance between the top plate member 1 and the outer surface member 3 to be constant, can be used for the pallet.

In FIG. 4, two corrugated-plate-like core materials 4 are adhered to each other in such a way that one core material is shifted by 90 degrees with respect to the other. The core material is made of a highly-compressed-molded article and configured to be a continuous wave shape in cross section. The shape of the waves each has same height and continuously connected in a certain direction. Preferably, the wave shape is configured to have a flat shape at its top portion so as to secure a wide adhesion area. Three or more corrugated-plane-like core material 4 may be laminated and adhered.

The shift amount between the two corrugated-plane-like core materials 4 is not limited to 90 degrees, but can be set to any degrees from 1 to 90 degrees. According to the high density compression molding method of the present invention, corrugation can be shaped in any direction through compression molding without generating offcut by adjusting the direction of the raw plane-laminated paper in the molds.

Adhesive is applied at least on a contact portion between the top plate member 1 and the top portion of the corrugation of the corrugated-plane-like-core material 4, a contact portion between the top portions of the corrugations of two corrugated-plane-like core materials 4 and a contact portion between the top portion of the corrugation of the corrugated-plane-like-core material 4 and the outer surface member 3. When importance is weighed on saving time and labor ration rather than saving the amount of adhesive, adhesive may be applied on whole area of the upper surface of the top plate member 1, both surfaces of the corrugated-plate-like core material 4 and a rear surface of the outer surface member 3.

On the surface of the outer surface member 3, a convexo-concave shape or a three-dimensional shape, which is in concert with the shape of the load to be carried (conveyed), can be formed at the time of the compression molding. When loads to be carried have a spherical or cylindrical shape and are easy to roll, or the load has bottom that is shaped into convexo-concave shape, it can not stand stably on its own bottom. In such cases the surface of the outer surface member 3 is shaped to fit the loads so as to prevent the loads from rolling or jolting. Pallet for loads having specific shape can be realized.

Fourth Embodiment

FIG. 7 is a perspective view showing the fourth embodiment of the present invention.

In the fourth embodiment, a leg portion strengthening plate 7 made of a highly compressed molded article is adhered to the bottom surfaces of every leg member with water soluble adhesive to strengthen and stabilize the leg portion and make the pallet have structural rigidity in all.

Further, as the bottom surface is made flat, the upper surfaces of the lower loads are prevented from generation of round traces caused by the cylinder-with-base-type leg 2 when the pallets are built up.

INDUSTRIAL APPLICABILITY

In the present invention, the pallet can be used as the paperboard three-dimensionally molded pallet having a sufficient rigidity in the load carrying surface and sufficient load-bearing strength in the leg portion. And when it is finally treated as a waste, it can be recycled as a new paperboard three-dimensionally molded pallet or a material for other paper products requiring rigidity without the need to sort its parts by material.

REFERENCE NUMERALS

-   1 top plate member -   2 cylinder-with-base type leg -   3 outer surface member -   4 corrugated-plate-like core material -   5 reinforced corrugated board -   6 raw pattern paper -   7 leg portion strengthening plate -   8 side end rising portion -   15 through hole -   16 recess -   17 cutout (small) -   18 cutout (large) -   19 wall surface valley-fold position (dashed line) -   20 flange mountain-fold position (dashed-dotted line) 

1. A paperboard three-dimensionally molded pallet comprising: a plane top plate member made of paper; and a cylinder-with-base type leg member made of paper; wherein a plurality of through holes is provided in the top plate member, a portion of the leg member is inserted into the through hole and joined to the top plate member using water soluble adhesive, and the top plate member and the leg member are made through highly-compressed molding process in which a water absorbed plane laminated paper as a raw material is placed into a mold and then molded into a prescribed shape through a pressurized thermal dehydration process.
 2. A paperboard three-dimensionally molded pallet according to claim 1, wherein the top plate member is formed with a rising sidewall at a side end portion thereof and on a plane portion of an inner side of the sidewall, a reinforced corrugated board is joined using a water soluble adhesive.
 3. A paperboard three-dimensionally molded pallet according to claim 1, wherein the top plate member comprises: a plate-like core material having convexo-concave shape in cross section; and a plate-like outer member having a size capable of covering a top surface and/or a rear surface of the core material being arranged on and joined to the core material using a water soluble adhesive.
 4. A paperboard three-dimensionally molded pallet according to claim 1, wherein the cylinder-with-base-type leg member comprises: a round bottom surface; a wall surface having an arcuate shape in cross section, which rises upward from the round bottom surface; and an outward flange extending horizontally outward from the wall surface, an upper surface of the top plate member and the flange portion of the leg member being joined together.
 5. A paperboard three-dimensionally molded pallet according to claim 4, wherein the wall surface of the leg members has a plurality of divided wall surfaces divided into 3 to 8 along a circumferential direction of the leg member and adjacent side edges of the divided wall surfaces are contacted with or placed close to each other.
 6. A paperboard three-dimensionally molded pallet according to claim 5, wherein a plurality of the cylinder-with-base type leg members are superimposed in such a way that the side edges of the superimposed divided-wall surfaces of the leg member are arranged along the circumferential direction without overlapping with each other.
 7. A paperboard three-dimensionally molded pallet according to claim 1, wherein at a circumferential portion of the through hole of the top plate member, a concave portion having a depth with a same dimension as the thickness of the flange portion is provided.
 8. A paperboard three-dimensionally molded pallet according to claim 1, wherein a bottom plate having a size large enough to join all the leg members is joined onto the bottom surfaces of the leg members using water soluble adhesive. 